Wireless communications method and apparatus

Abstract

A method of relaying a signal in a wireless communications network including a plurality of wireless devices is performed by at least one of said wireless devices to relay a signal in a communication path between one of said plurality of wireless devices and another one of said wireless devices, wherein said at least one of said wireless devices includes a power amplifier for amplifying said signal, the method including receiving a signal from said one of said plurality of wireless devices, determining a peak-to-average power ratio of said received signal under a plurality of predetermined relay modes, determining a back-off value associated with said power amplifier, selecting a mode of relaying said signal from said plurality of predetermined relay modes based on said determined peak-to-average power ratio and said determined back-off value, and transmitting said signal to said another one of said plurality of wireless devices using said selected mode.

The invention claimed is: 
     
       1. A method of relaying a signal in a wireless communications network comprising a plurality of wireless devices, the method being performed by at least one of said wireless devices to relay a signal in a communication path between one of said plurality of wireless devices and another one of said wireless devices, wherein said at least one of said wireless devices comprises a power amplifier for amplifying said signal, the method comprising:
 receiving a signal from said one of said plurality of wireless devices; 
 determining, for each one of a plurality of predetermined relay modes, a respective peak-to-average power ratio that a reference signal is expected to exhibit in the event that the respective predetermined relay mode is used for relaying the reference signal; 
 determining a back-off value associated with said power amplifier; 
 selecting a mode of relaying said received signal from said plurality of predetermined relay modes based on said determined peak-to-average power ratios and said determined back-off value; and 
 transmitting said signal to said another one of said plurality of wireless devices using said selected mode. 
 
     
     
       2. The method according to  claim 1 , wherein said selecting mode of relaying said signal is performed such that the peak-to-average power ratio of said reference signal is less than or equal to the back-off value. 
     
     
       3. The method according to  claim 1 , wherein said plurality of predetermined relay modes includes a decode-and-forward mode, a fixed gain amplify-and-forward mode, and a variable gain amplify-and-forward mode. 
     
     
       4. A relay device for relaying a signal in a wireless communications network comprising a plurality of wireless devices, the relay device being configured to relay said signal in a communication path between one of said plurality of wireless devices and another one of said plurality of wireless devices, the relay device comprising:
 a receiver for receiving a signal from one of said plurality of wireless devices; 
 a power amplifier for amplifying said received signal; 
 a processor configured to determine, for each one of a plurality of predetermined relay modes, a respective peak-to-average power ratio that a reference signal is expected to exhibit in the event that the respective predetermined relay mode is used for relaying the reference signal, and to determine a back-off value associated with said power amplifier; 
 a selector for selecting a mode of relaying said received signal from said plurality of predetermined relay modes based on said determined peak-to-average power ratios and said determined back-off value; and 
 a transmitter for transmitting said received signal to said another one of said plurality of wireless devices using said selected mode. 
 
     
     
       5. The relay device according to  claim 4 , wherein said selector is configured to select a mode of relaying said received signal such that the peak-to-average power ratio of the received signal is less than or equal to the back-off value. 
     
     
       6. The relay device according to  claim 4 , wherein said plurality of predetermined relay modes includes a decode-and-forward mode, a fixed gain amplify-and-forward mode, and a variable gain amplify-and-forward mode. 
     
     
       7. A non-transitory computer readable storage medium comprising computer executable instructions which, when executed by a computer in a wireless device, are operable to cause said computer to:
 receive a signal from another wireless device; 
 determine a respective peak-to-average power ratio of a reference signal for each one of a plurality of predetermined relay modes; 
 determine a back-off value associated with a power amplifier associated with one of the wireless devices; 
 select a mode of relaying said received signal from said plurality of predetermined relay modes based on said determined peak-to-average power ratios and said determined back-off value; and 
 transmit said signal to said another wireless device using said selected mode.